Material composition and shaped article

ABSTRACT

A material composition comprising (a) a poly-functional isocyanate, (b) a compound having MW of 600-3,500 and two functional groups polymerizable with an isocyanate group, (c) a compound having MW below 500 and two functional groups polymerizable with an isocyanate group, and (d) a compound having MW below 700 and at least three functional groups polymerizable with an isocyanate group. A shaped polymeric material is made by mixing and heating (a) with part of (b) to give a prepolymer, adding the remainder of (b), (c) and (d) to the prepolymer, and then heating the mixture to effect additional polymerization of (a), (b), (c) and (d). The shaped polymeric material has enhanced tear strength, tensile strength and elongation, reduced permanent set and low toxicity, and suitable for parts for which high stretchability is required.

DESCRIPTION

1. Technical Field

This invention relates to a shaped article and a material composition.More particularly, it relates to a medical shaped article used as partsfor which a high stretchability is required, such as a balloon of acatheter, and having a low toxicity, a high tear strength, a hightensile strength, a large elongation and a reduced permanent set, and toa material composition used for the medical shaped article.

2. Background Art

For medical articles used as treating living bodies such as a catheterand an artificial vessel, a low toxicity, a high tear strength, a hightensile strength, a large elongation and a reduced permanent set arerequired.

As a material used for a shaped article such as a balloon of a catheter,natural rubber is well known. However, it has recently been found thatnatural rubber contains a trace amount of protein and causes abiological allergic reaction. Therefore a material composition which canbe a substitute for natural rubber is eagerly desired.

As a natural rubber substitute, a thermoplastic polyurethane is known. Athermoplastic polyurethane is a polymer prepared by a polycondensationreaction between approximately equimolar amounts of a diisocyanate and adiol or diamine. However, as is known in the art, in the case where athermoplastic polyurethane is used for a part such as a catheterballoon, for which a 500% or higher elongation is required, when theballoon contracts, it is creased and a blood stream becomes locallystagnant and a salient amount of thrombus is produced. Further, a shapedarticle made of a thermoplastic polyurethane has a low tensile strengthand elongation, as compared with natural rubber, and a large permanentset. Thus a thermoplastic polyurethane cannot be a perfect substitutefor natural rubber.

It is conducted that molecule chains of a thermoplastic polyurethane arecrosslinked with a cross-linking agent having at least three functionalgroups or other crosslinkers to reduced the permanent set of thethermoplastic polyurethane. However, the crosslinked thermoplasticpolyurethane has a low tensile strength and tear strength, and thereforeis not suitable for shaped articles for which high tenacities arerequired.

DISCLOSURE OF INVENTION

An object of the present invention is to provide a shaped articlesuitable as parts for which a high stretchability is required, andhaving a low toxicity, a high tear strength, a high tensile strength, alarge elongation and a reduced permanent set, and to a materialcomposition used for the shaped article.

The inventors have conducted researches to achieve the above objects,and found that, when a polyurethane made by using a specific chainextender is used, the above object can be achieved, and completed thepresent invention.

In accordance with the present invention, there is provided a materialcomposition characterized as comprising, as the essential ingredients:

(a) a polyfunctional isocyanate,

(b) a compound having a molecular weight of 600 to 3,500 and twofunctional groups capable of being additionally polymerized with anisocyanate group,

(c) a compound having a molecular weight not larger than 500 and twofunctional groups capable of being additionally polymerized with anisocyanate group, and

(d) a compound having a molecular weight not larger than 700 and atleast three functional groups capable of being additionally polymerizedwith an isocyanate group;

the sum of the functional groups capable of being additionallypolymerized with an isocyanate group, in compounds (c) and (d), is 1 to35 moles per 100 moles of the isocyanate groups in polyfunctionalisocyanate (a),

the amount of the functional group capable of being additionallypolymerized with an isocyanate group, in compound (d), is 0.1 to 18moles per 100 moles of the isocyanate groups in polyfunctionalisocyanate (a),

the amount of the functional group capable of being additionallypolymerized with an isocyanate group, in compound (b), is 60 to 100moles per 100 moles of the isocyanate groups in polyfunctionalisocyanate (a), and

the sum of the functional groups capable of being additionallypolymerized with an isocyanate group, in compounds (b), (c) and (d), is80 to 110 moles per 100 moles of the isocyanate groups in polyfunctionalisocyanate (a).

In accordance with the present invention, there is further provided ashaped article made of a polymer prepared by additional polymerizationof polyfunctional isocyanate (a) with compound (b), compound (c) andcompound (d).

BEST MODE FOR CARRYING OUT THE INVENTION

The invention will now be described in detail in the following.

The material composition of the present invention comprises, as theessential ingredients, (a), a polyfunctional isocyanate, and compounds(b), (C) and (d) which have a specific molecular weight and functionalgroups capable of being additionally polymerized with an isocyanategroup.

Polyfunctional isocyanate (a) used in the material composition of thepresent invention is a compound having two isocyanate groups. Asspecific examples of polyfunctional isocyanate (a), there can bementioned aromatic diisocyanates such as diphenylmethane diisocyanate,naphthalene diisocyanate, tolylene diisocyanate, tetramethylxylenediisocyanate and xylene diisocyanate; and aliphatic diisocyanates suchas dicyclohexane diisocyanate, dicyclohexylmethane diisocyanate,hexamethylene diisocyanate and isophorone diisocyanate. Of thesepolyfunctional isocyanates, diphenylmethane diisocyanate is mostpreferable in view of high safety to living bodies.

Compound (b) used in the material composition of the present inventionis a compound having two functional groups capable of being additionallypolymerized with an isocyanate group. The functional group capable ofbeing additionally polymerized with an isocyanate group is a functionalgroup having active hydrogen. By the term "active hydrogen" used hereinis meant a hydrogen atom bonded to an oxygen atom or a nitrogen atomwhich constitute part of the compound. As specific examples of thefunctional group, there can be mentioned a hydroxyl group and an aminogroup.

Compound (b) having two functional groups capable of being additionallypolymerized with an isocyanate group (which group is hereinafterabbreviated to "functional group") has a molecular weight of at least600, preferably at least 700, and not higher than 3,500, preferably nothigher than 2,500. If the molecular weight of compound (b) is lower than600, a shaped article made by additionally polymerizing the materialcomposition has a poor tensile strength and a small elongation. Incontrast, if the molecular weight thereof exceeds 3,500, the materialcomposition becomes difficult to shaper and, even if it is possible toshape, the shaped article has an undesirably large permanent set. Themolecular weight of compound (b) means that as determined by measurementby gel permeation chromatography using tetrahydrofuran as a carrier andcalculation based on a calibration curve of the number average molecularweight of standard polystyrene.

Compound (b) having two functional groups preferably has a weightaverage molecular weight/number average molecular weight of not largerthan 2, preferably not larger than 1.9 If the ratio exceeds 2, theshaped article tends to have a large permanent set and a poor tensilestrength. The weight average molecular weight of compound (b) means thatas determined by measurement by gel permeation chromatography usingtetrahydrofuran as a carrier and calculation based on a calibrationcurve of the weight average molecular weight of standard polystyrene.

As specific examples of compound (b) having two functional groups, therecan be mentioned polyether-diols such as polyoxy-tetramethylene glycol,polyethylene glycol and polypropylene glycol, dehydration condensates ofa polycarboxylic acid such as adipic acid with a polyhydric alcohol suchas a glycol or a triol, a polyester-diol such as polycarbonate-diol, andpolybutadiene diol. Compound (b) may be used either alone or incombination. Among the these compounds (b), a polyetherdiol, especiallypolyoxy-tetramethylene glycol is preferable because of biologicalacceptability and safety,

The amount of compound (b) is such that the amount of the functionalgroup within compound (b) is 60 to 100 moles, preferably 70 to 95 moles,per 100 moles of the isocyanate group (when appropriate, hereinafterreferred to merely as "isocyanate group") within polyfunctionalisocyanate (a). If the amount of the functional group in compound (b) issmaller than 60 moles, the shaped article has a poor tensile strengthand a small elongation. In contrast, if the amount of the functionalgroup in compound (b) is larger than 100 moles, the shaped article has alarge permanent set.

Compound (c) used in the material composition of the present inventionis a compound having two functional groups.

Compound (c) has a molecular weight of not higher than 500, preferablynot higher than 400. The lower limit of the molecular weight is usuallyabout 30. If the molecular weight is larger than 500, the shaped articlehas a low tenacity. The molecular weight of compound (c) is determinedby mass spectrometry,

As specific examples of compound (c), there can be mentioned dials suchas ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanedioland 1,6-hexanediol, and diamines such as ethylenediamine,hexamethylenediamine, N,N'-diisopropylmethylenediamine andN,N'-di-sec.-butyl-p-phenylenediamine. Of these compounds (c),ethylenediamine and 1,4-butanediol are preferable because the shapedarticle has a high tenacity.

Compound (d) used in the material composition of the present inventionis a compound having at least three functional groups.

Compound (d) has a molecular weight of not higher than 700, preferablynot larger than 600. If the molecular weight thereof is higher than 700,the shaped article has a poor tenacity. The lower limit thereof isusually about 40. The molecular weight of compound (d) is determined bymass spectrometry,

As specific examples of compound (d), there can be mentioned tri- ormore functional polyols such as glycerine, trimethylolpropane,pentaerythritol, sorbitol, methylene glycoside,N-tetrapropinol-diethylamine and sucrose, and tri- or more functionalpolyamines such as 1,3,5-triamino-benzene. Of these compounds (d),trimethylolpropane is preferable.

Among the combinations of compound (c) with compound (d), a combinationof ethylenediamine or 1,4-butanediol as compound (c) withtrimethylolpropane as compound (d) is preferable in order to provide ashaped article having a high tear strength, a high tensile strength anda small permanent set.

The sum of compound (c) and compound (d) is such that the total amountof the functional groups in compound (c) and compound (d) is 1 to 35moles, preferably 3 to 35 moles, per 100 moles of the isocyanate group.

The amount of compound (c) is such that the amount of the functionalgroup in compound (c) is 0.9 to 34.9 moles, preferably 2 to 34 moles,per 100 moles of the isocyanate group.

The amount of compound (d) is such that the amount of the functionalgroup in compound (d) is 0.1 to 18 moles, preferably 1 to 10 moles, per100 moles of the isocyanate group.

The ratio of compound (c) to compound (d) is such that the ratio of theamount of the functional group in compound (c) to the total amount ofthe functional group in compound (c) plus compound (d) is 70 to 97% bymole, preferably 80 to 95% by mole, and that the ratio of the amount ofthe functional group in compound (d) to the total amount of thefunctional group in compound (c) plus compound (d) is 3 to 30% by mole,preferably 5 to 20% by mole. If the relative amount of compound (c) istoo small, the shaped article tends to have a poor elongation and a lowtear strength. In contrast, if the relative amount of compound (c) istoo large, there is a tendency to reduce the effect of enhancing tearstrength and tensile strength of the shaped article.

The sum of compound (b), compound (c) and compound (d) is such that thetotal amount of the functional group in compound (b), compound (c) pluscompound (d) is 80 to 110 moles, preferably 85 to 105 moles, and morepreferably 90 to 105 moles, per 100 moles of the isocyanate groups Thesum of the three compounds is outside this range, the shaped article hasa large permanent set.

According to the need, the material composition of the present inventionmay have incorporated therein additives, which include fillers such ascolloidal silica, white carbon and calcium carbonate; plasticizers suchas dibutyl phthalate, di(2-ethylhexyl) phthalate and di(2-ethylhexyl)adipate; softeners such as white oil and paraffin, and reactionpromotors for the reaction of polyfunctional isocyanate (a) withcompound (b), compound (c) and compound (d) such as a tertiary amine andan alkyl-tin.

The configuration of the material composition of the present inventionis not particularly limited, A material composition prepared by aprocess wherein a mixture of polyfunctional isocyanate (a), part ofcompound (b), part of compound (c) and part of compound (d) isheat-melted, and a mixture of the remainders of compound (b), compound(c) and compound (d) is heat-melted, and then the two molten mixturesare mixed together, can be shaped into a shaped article by casting themolten mixture in a mold. A material composition prepared by dissolvingpolyfunctional isocyanate (a), compound (b)e compound (c) and compound(d) in an organic solvent can be shaped into a shaped article by a dipforming method. It is preferable that the solution in an organic solventfor dip forming contains compound (b), compound (c) and compound (d) inamounts such that the total amount of functional groups in the sum ofcompound (b), compound (c) and compound (d) is not larger than 95 molesper 100 moles of the isocyanate groups in the polyfunctional isocyanate(a). If the total amount of functional groups in compound (b), compound(c) and compound (d) exceeds 95 moles, premature additionalpolymerization of the polyfunctional isocyanate (a) with compound (b),compound (a) and compound (d) occurs and the solute is liable to bedeposited, and thus, the dip forming of the, solution becomes difficult.

The organic solvent used for the preparation of the forming solution isusually either incompatible with water or, when it is compatible withwater, the aqueous solution of the organic solvent has a pH value of 6to 8. As specific examples of the organic solvent, there can bementioned aromatic hydrocarbons such as benzene, toluene and xylene;ethers such as tetrahydrofuran and cyclohexanone; ketones such as methylethyl ketone and isobutyl ethyl ketone; aliphatic hydrocarbons such ashexene and hexane; and acetonitrile, dimethylsulfoxide,N,N-dimethylformamide and dimethylacetamide.

The method for preparing the material composition of the presentinvention is not particularly limited. Various methods can be employed,which include, for example, a method wherein polyfunctional isocyanate(a) is mixed with compound (b), and then compound (c) and compound (d)are added; a method compound (b), compound (c) and compound (d) aremixed together and then polyfunctional isocyanate (a) is added; and amethod wherein polyfunctional isocyanate (a) is mixed with part ofcompound (b), and then the remainder of compound (b), compound (c) andcompound (d) are added. Of these methods, the method whereinpolyfunctional isocyanate (a) is mixed with part of compound (b), andthen the remainder of compound (b), compound (c) and compound (d) areadded is preferable because a shaped article having a high tensilestrength is obtained.

In the method wherein polyfunctional isocyanate (a) is mixed with partof compound (b) at the first step, and the remainder of compound (b),compound (c) and compound (d) are added at the second step, the amountof compound (b) mixed with polyfunctional isocyanate (a) at the firststep is such that the amount of the functional group in the compound (b)is usually 35 to 65 moles, preferably 40 to 60 moles, per 100 moles ofthe isocyanate group. If the amount of the functional group in thecompound (b) is larger than 65 moles or smaller than 35 moles, theeffect of enhancing the tensile strength is occasionally reduced.

At the time when or after polyfunctional isocyanate (a) is mixed withpart of compound (b), it is preferable to heat the mixture of (a) with(b). By heating the mixture, polyfunctional isocyanate (a) isadditionally polymerized with part of compound (b). The heatingtemperature is usually 50° to 100° C., preferably 60° to 90° C. When theheating temperature is lower than 50° C., a long period of time isrequired for completion of the additional polymerization. When theheating temperature is higher than 100° C., the procedure at the secondstep becomes difficult to conduct, as well as the shaped article has alarge permanent set, and poor tensile strength, tear strength andelongation. The heating time is usually 10 to 480 minutes, preferably 30to 120 minutes.

After the completion at the first step, the remainder of compound (b),compound (c) and compound (d) are added. The amount of compound (b)added at the second step is such that the amount of the functional groupin compound (b) is usually 5 to 65 moles, preferably 10 to 60 moles, per100 moles of the isocyanate group.

An additional polymerization of polyfunctional isocyanate (a) withcompound (b), compound (c) and compound (d) in the material compositionof the present invention and a shaping of the polymerization mixtureresult in a shaped polymeric article.

The additional polymerization is carried out during, after or before theshaping. Preferably it is carried out during the shaping. The shaping isconducted usually by a melt shaping method, a casting shaping method, adipping shaping method or a reaction extrusion shaping method. Of these,a reaction extrusion shaping method is preferable.

For the reaction extrusion shaping method, a procedure is employedwherein a molten material composition is extruded under heatedconditions, while being, additionally polymerized, into a mold of adesired shape, followed by continuation of heating in the mold tocomplete the additional polymerization.

The additional polymerization is effected by heating the materialcomposition. Preferably the heating is conducted after volatileingredients such as a solvent and a dispersing medium, and air(contained as foams) are removed to an extent such that the total amountof these ingredients remaining in the material composition is usuallynot larger than 1% by weight, preferably not larger than 0.1% by weight.When the amount of such ingredients is larger than 1% by weight, thematerial composition is foamed upon heating and a shaped polymericarticle having cells therein is produced.

When a reaction promotor is not used, the heating temperature is usually60° to 170° C., preferably 100° to 130° C. At a temperature lower than60° C., the additional polymerization is difficult to conduct. Incontrast, at a temperature higher than 170° C., decomposition reactionsoccur and the shaped article is liable to be deteriorated. The heatingtime varies depending upon the particular shape of the shaped article,but is usually in the range of 6 to 120 hours, preferably 12 to 48hours. When the heating time is short, the shaped article has a largepermanent set, In contrast, when the heating time is long, the shapedarticle has a poor tensile strength. A reaction promotor can be added topromote the additional polymerization. As examples of the reactionpromotor, there can be mentioned tertiary amines and organic tincompounds. By using the reaction promotor, the additional polymerizationcan be completed at a relatively low heating temperature and for a shortperiod of time.

After completion of the additional polymerization, the polymerizationproduct (i.e., shaped polymeric material) is usually allowed to standfor 4 to 14 days at room temperature to age the shaped article. By theaging, the permanent set of the shaped article is desirably reduced.

The shaped article of the present invention has a tensile strength atbreak of usually in the range of 15 to 50 MPa, preferably 18 to 40 MPa,an elongation at break of usually at least 550%, preferably at least600% and more preferably at least 700%, and a permanent set (anelongation as measured after a tensile load is removed) of usuallysmaller than 20%, preferably not larger than 15%.

The invention will now be described specifically by the followingexamples, but should not be construed to be limited thereto.

The evaluation methods employed in the examples are as follows.

Tensile Test

A dumbbell specimen is punched out from a polymer sheet having athickness of 2 mm by using a #3 dumbbell die as stipulated in JapaneseIndustrial Standard K6301, and gauge marks are drawn at an interval of 2cm in the drawing direction on the surface of the specimen. The specimenis drawn at a grip distance of 20 mm and a grip separating rate of 400mm/min under conditions of temperature of 23° C. and relative humidityof 65%, and the tensile strength and elongation at break are measured.

Permanent Set

A dumbbell specimen is punched out from a polymer sheet having athickness of 2 mm by using a #3 dumbbell die as stipulated in JapaneseIndustrial Standard K6301, and gauge marks are drawn at an interval of 2cm in the drawing direction on the surface of the specimen. The specimenis drawn at a grip distance of 20 mm and a grip separating rate of 400mm/min under conditions of temperature of 23° C. and relative humidityof 65% until the specimen reaches an elongation of 500%. The specimen ismaintained at the drawn state for 10 minutes. After the tensile load isremoved, the specimen is allowed to stand for 10 minutes and thedistance (m) between two gauge marks is measured. The permanent set iscalculated as the ratio in % of the difference between the gauge markdistance (m) as measured after the tensile load is removed and the gaugemark distance as measured before drawing. (i.e., 2 cm) to the latterdistance (2 cm).

Tear Test

A specimen having a rectangular shape with a length of 60 mm and a widthof 12 mm, one long side of which has a notch, i.e., a V-shapedindentation having a depth of 2 mm at the center thereof (saidindentation having a shape of triangle right-angled at the bottom of theV-shaped indentation), is punched out from a polymer sheet having athickness of 2 mm. The specimen is drawn by the same procedure and underthe same conditions as those employed for the tensile test, and the tearstrength at break is measured.

Antithrombotic Property

A balloon catheter is inserted through the aorta to the vicinity of theright atrium of a goat, and physiologic saline is injected into thecatheter to expand the balloon to a diameter of 1 cm. The catheter isallowed to stand for 10 minutes as the balloon is expanded, and then isdeflated. Thirty minutes after the deflation, the catheter is withdrawnfrom the aorta, and the surface of the balloon is observed by the nakedeye to check the occurrence of thrombus. The observation results areexpressed by the following three ratings.

A: No thrombus occurred.

B: Thrombus occurred only to a slight extent such that the health ofgoat is not injured even though the catheter is repeatedly used.

C: Thrombus occurred to an extent such that repeated use of the catheteris apt to injure the health of goat.

Collective Evaluation as Material for Catheter Balloon

A material having a tensile strength of at least 15 MPa, an elongationof at least 550%, a permanent set of not larger than 20% and anantithrombosis of rating A is acceptable (expressed as "A"). Especiallya material having a tensile strength of at least 20 MPa, an elongationof at least 600%, a permanent set of not larger than 15% and anantithrombosis of rating A is of excellent quality (expressed as "E"). Amaterial not satisfying the above-mentioned acceptance criteria isunacceptable (expressed as "C").

Antikinking Property

A tube with a diameter of 2.3 mm for a catheter is placed at roomtemperature (20° C.) on two supporting blocks arranged at an interval of40 mm , and a point of the tube positioned at equal distance from thetwo support blocks is pushed down at a rate of 5 mm/min. When kinkingoccurs, the distorted length of the pushed point (i.e., the depth of theV-shaped distorted tube) is measured,

Distortion Recovery

Both ends of a tube for a catheter having an axial length of 200 mm anda diameter of 23 mm are connected into a loop form by a self-adhesivetape, and the loopy tube is placed in a thermostatic chamber andmaintained at 50° C. for 30 minutes. Then, the self-adhesive tape isremoved and the tube is allowed to stand in a chamber maintained at atemperature of 20° C. for 10 minutes. Then the length (L in mm) of asegment of a straight line extending from one end of the tube to theother end thereof is measured. The distortion recovery (%) is calculatedfrom the equation:

    Distortion recovery (%)=(L/200)×100

Collective Evaluation as Catheter Tube

A material having an antikinking degree of at least 25 mm and an ratioof distortion in length of at least 80% is acceptable and expressed as"A". A material not satisfying these acceptance criteria is expressed as"C"

Evaluation of Adhesion Retention

Two sheets of the same antithrombotic material are adhered to respectivepumps of two auxiliary artificial hearts. One sheet is peeled at 37° C.and a peeling rate of 100 mm/min, and the strength (A) (kN/m) thereof ismeasured. The other sheet adhered to the pump is drawn to an elongationof 5% at 37° C. and this drawing is repeated 200,000 times. Thereafter,the sheet is peeled at 37° C. and a peeling rate of 100 mm/min, and thestrength (B) (kN/m) thereof is measured. The adhesion retention isexpressed by the ratio in % of the strength (B) as measured after therepeated drawing to the strength (A) as measured before the repeateddrawing.

Example 1

A reactor flashed with nitrogen was charged with 100 milli-moles ofdiphenylmethane diisocyanate and 50 milli-moles of polyoxytetramethyleneglycol having a number average molecular weight of 1,000 and a weightaverage molecular weight/number average molecular weight ratio of 1.86.The content was stirred at 90° C. for one hour to conduct an additionalpolymerization whereby a urethane prepolymer was obtained.

Into the reactor containing the urethane prepolymer, 25 milli-moles ofpolyoxytetramethylene glycol having a number average molecular weight of1,000 and a weight average molecular weight/number average molecularweight ratio of 1.86, 22 millimoles of 1,4-butanediol and 2 millimolesof trimethylolpropane as chain extender were added at 70° C. The mixturewas stirred and deaerated for 3 minutes by using a vacuum pump whereby amaterial composition was obtained.

The thus-obtained material composition was cast into a space (distance:2 mm) between a pair of square iron sheets each having a size of 10cm×10 cm, and heated at 110° C. for 24 hours to give a shaped article ofa sheet-shape. The evaluation results of the sheet are shown in Table 1.

The above-mentioned urethane prepolymer and the above-mentioned chainextender were maintained at 70° C. and mixed together at thattemperature by a mixer provided with a gear pump at a rate of 2 ml/minand at a pressure of 5 atm. The thus-obtained mixture (which is amaterial composition for medical use) was introduced into a column of anextruder having an inner volume of about 10 ml and maintained at atemperature of 130° to 170° C. where the mixture was subjected to anadditional polymerization and extruded through a nozzle to form acoating around a core made of stainless steel wires with a diameter of1.8 mm.

The coated stainless steel wire core was cooled by using a blower,traveled on a conveyor, and out by a cutter into a length of 5 to 12 cm.The cut product was heated at 110° C. for 24 hours and then immersed inan aqueous solution containing 70% of ethanol for 4 hours. Thereafter,the tublar coating was demolded from the stainless steel wire core,dried at 70° C. and then adjusted to a length of 1.5 cm.

The thus-prepared tube was fitted to a tip of an intravascular dwellingcatheter so that the tube covers an opening for balloon on the wall ofthe tip portion of the tube to prepare a balloon catheter. Theevaluation results of antithrombotic properly of the catheter balloonare shown in Table 1.

Examples 2 to 22 and Comparative Example 1 to 6

By the same procedures as described in Example 1, material compositions,sheets and balloon catheters were prepared wherein the compounds usedand amounts thereof were varied as shown in Tables 1 through 5 with allother conditions remaining the same. The evaluation results of thesheets and balloon catheters are shown in Table 1 through Table 5.

                  TABLE 1                                                         ______________________________________                                                     Examples                                                                      1       2       3     4     5                                    ______________________________________                                        Prepolymer                                                                    Polyfunctional                                                                isocyanate (a)  m-mol!                                                        Diphenylmethane                                                                            100     100     100   100   100                                  diisocyanate                                                                  Compound (b)  m-mol!                                                          Polyoxytetramethylene                                                                      50      50      50    50    50                                   glycol                                                                        Number average                                                                             1000    1500    1000  1000  2000                                 molecular weight (Mn)                                                         Mw/Mn ratio *1                                                                             1.86    1.68    1.86  1.86  1.86                                 Chain extender                                                                Compound (b)  m-mol!                                                          Polyoxytetramethylene                                                                      25      12      48    44    21                                   glycol                                                                        Number average                                                                             1000    1500    1000  1000  1000                                 molecular weight (Mn)                                                         Mw/Mn ratio *1                                                                             1.86    1.68    1.86  1.86  1.86                                 Compound (c)  m-mol!                                                                       22      20      1.85  1     17                                   1,4-Butanediol                                                                Compound (d)  m-mol!                                                                       2       2       0.1   0.13  10                                   Trimethylolpropane                                                            Tensile strength  MPa!                                                                     34      18      30    28    21                                   Elongation  %!                                                                             700     620     840   810   590                                  Permanent set  %!                                                                          4       10      18    17    13                                   Tear strength  kN/m!                                                                       50      28      40    35    40                                   Antithrombotic property                                                                    A       A       A     A     A                                    Collective evaluation                                                                      E       A       A     A     A                                    as balloon material                                                           ______________________________________                                         *1 Mw/Mn ratio: Ratio of weight average molecular weight/number average       molecular weight                                                         

                  TABLE 2                                                         ______________________________________                                                     Examples                                                                      6       7       8     9     10                                   ______________________________________                                        Prepolymer                                                                    Polyfunctional                                                                isocyanate (a)  m-mol!                                                        Methylenedicyclohexane-                                                                    --      --      --    --    100                                  4,4'-diisocyanate                                                             Diphenylmethane                                                                            100     100     100   100   --                                   diisocyanate                                                                  Compound (b)  m-mol!                                                                       50      50      50    50    50                                   Polyoxytetramethylene                                                         glycol                                                                        Number average                                                                             1000    750     2000  1000  1000                                 molecular weight (Mn)                                                         Mw/Mn ratio *1                                                                             1.85    1.85    1.81  1.86  1.86                                 Chain extender                                                                Compound (b)  m-mol!                                                                       13      43      13    23    23                                   Polyoxytetramethylene                                                         glycol                                                                        Number average                                                                             1000    750     2000  1000  1000                                 molecular weight (Mn)                                                         Mw/Mn ratio *1                                                                             1.86    1.85    1.81  1.86  1.86                                 Compound (c)  m-mol!                                                          Ethylenediamine                                                                            --      --      --    --    18                                   1,4-Butanediol                                                                             26      1.3     18    1.3   --                                   Compound (d)  m-mol!                                                          Glycerine    --      --      --    --    1.3                                  Trimethylolpropane                                                                         6.7     0.13    2.7   0.13  --                                   Tensile strength  MPa!                                                                     33      22      25    20    28                                   Elongation  %!                                                                             570     620     700   610   560                                  Permanent set  %!                                                                          18      17      18    16    17                                   Tear strength  kN/m!                                                                       42      40      31    30    33                                   Antithrombotic property                                                                    A       A       A     A     A                                    Collective evaluation                                                                      A       A       A     A     A                                    as balloon material                                                           ______________________________________                                         *1 Mw/Mn ratio: Ratio of weight average molecular weight/number average       molecular weight                                                         

                  TABLE 3                                                         ______________________________________                                                     Examples                                                                      11      12      13    14    15                                   ______________________________________                                        Prepolymer                                                                    Polyfunctional                                                                isocyanate (a)  m-mol!                                                        Diphenylmethane                                                                            100     100     100   100   100                                  diisocyanate                                                                  Compound (b)  m-mol!                                                          Polyoxytetramethylene                                                                      50      50      50    --    --                                   glycol                                                                        Polypropylene oxide                                                                        --      --      --    50    --                                   Ethylene oxide/propy-                                                                      --      --      --    --    50                                   lene oxide copolymer                                                          Number average                                                                             2700    650     1000  1000  1000                                 molecular weight (Mn)                                                         Mw/Mn ratio *1                                                                             1.83    1.85    1.86  1.86  1.86                                 Chain extender                                                                Compound (b)  m-mol!                                                          Polyoxytetramethylene                                                                      16      44      23    --    --                                   glycol                                                                        Polypropylene oxide                                                                        --      --      --    23    --                                   Ethylene oxide/propy-                                                                      --      --      --    23    --                                   lene oxide copolymer                                                          Number average                                                                             2700    650     1000  1000  1000                                 molecular weight (Mn)                                                         Mw/Mn ratio *1                                                                             1.83    1.85    1.86  1.86  1.86                                 Compound (c)  m-mol!                                                          1,4-Butanediol                                                                             32      3       --    18    18                                   1,4-Dimethylolbenzene                                                                      --      --      18    --    --                                   Compound (d)  m-mol!                                                          Trimethylolpropane                                                                         1.3     1.3     --    1.3   1.3                                  Ethylenediamine                                                                            --      --      1.3   --    --                                   tetraethanol                                                                  Tensile strength  MPa!                                                                     40      22      43    36    32                                   Elongation  %!                                                                             800     580     800   900   820                                  Permanent set  %!                                                                          17      7       16    18    16                                   Tear strength  kN/m!                                                                       31      29      39    37    31                                   Antithrombotic property                                                                    A       A       A     A     A                                    Collective evaluation                                                                      A       A       A     A     A                                    as balloon material                                                           ______________________________________                                         *1 Mw/Mn ratio: Ratio of weight average molecular weight/number average       molecular weight                                                         

                  TABLE 4                                                         ______________________________________                                                      Examples                                                                      16     17     18   19   20    21                                ______________________________________                                        Prepolymer                                                                    Polyfunctional                                                                isocyanate (a)  m-mol!                                                        Diphenylmethane                                                                             100    100    100  100  100   100                               diisocyanate                                                                  Compound (b)  m-mol!                                                          Polyoxytetramethylene                                                                       50     50     45   55   50    50                                glycol                                                                        Number average                                                                              1100   1000   1000 1000 1000  1000                              molecular weight                                                              Mw/Mn ratio *1                                                                              1.86   1.86   1.86 1.86 2.1   2.3                               Chain extender                                                                Compound (b)  m-mol!                                                          Polyoxytetramethylene                                                                       33     23     30   20   25    23                                glycol                                                                        Number average                                                                              1100   1000   1000 1000 1000  1000                              molecular weight (Mn)                                                         Mw/Mn ratio *1                                                                              1.86   1.86   1.86 1.86 2.1   2.3                               Compound (c)  m-mol!                                                          1,4-Butanediol                                                                              9.6    18     22   22   22    18                                Compound (d)  m-mol!                                                          Trimethylolpropane                                                                          0.26   1.3    2    2    2     1.3                               Tensile strength  MPa!                                                                      16     37     27   28   15    19                                Elongation  %!                                                                              820    840    710  620  570   610                               Permanent set  %!                                                                           17     10     13   14   19    20                                Tear strength  kN/m!                                                                        42     33     45   30   40    31                                Antithrombotic property                                                                     A      A      A    A    A     A                                 Collective evaluation                                                                       A      E      E    E    A     A                                 as balloon material                                                           ______________________________________                                         *1 Mw/Mn ratio: Ratio of weight average molecular weight/number average       molecular weight                                                         

                  TABLE 5                                                         ______________________________________                                                      Comparative Examples                                                          1      2      3    4    5     6                                 ______________________________________                                        Prepolymer                                                                    Polyfunctional                                                                isocyanate (a)  m-mol!                                                        Diphenylmethane                                                                             100    100    100  100  100   100                               diisocyanate                                                                  Compound (b)  m-mol!                                                          Polyoxytetramethylene                                                                       50     56     50   50   50    50                                glycol                                                                        Number average                                                                              1000   1000   1000 400  4000  1000                              molecular weight (Mn)                                                         Mw/Mn ratio *1                                                                              1.86   1.86   1.86 2.4  2.2   1.86                              Chain extender                                                                Compound (b)  m-mol!                                                          Polyoxytetramethylene                                                                       7      53     8    25   25    28                                glycol                                                                        Number average                                                                              1000   1000   1000 400  4000  1000                              molecular weight (Mn)                                                         Mw/Mn ratio *1                                                                              1.86   1.86   1.86 2.4  2.2   1.86                              Compound (c)  m-mol!                                                          1,4-Butanediol                                                                              18     6      20   22   22    22                                Compound (d)  m-mol!                                                                        1.3    2      14.7 2    2     --                                Trimethylolpropane                                                            Tensile strength  MPa!                                                                      13     18     13   25   *2    18                                Elongation  %!                                                                              480    990    320  400        690                               Permanent set  %!                                                                           2      24     --   8          35                                Tear strength  kN/m!                                                                        20     32     17   50         32                                Antithrombotic property                                                                     A      A      --   B          C                                 Collective evaluation                                                                       C      C      C    C    C     C                                 as balloon material                                                           ______________________________________                                         *1 Mw/Mn ratio: Ratio of weight average molecular weight/number average       molecular weight                                                              *2 Sheet could not be made                                               

As seen from the above data, when the amount of compound (b) is small(Comparative Example 1) or the amount of compound (d) is large(Comparative Example 3), the tensile strength and tear strength arereduced.

When the amount of compound (b) is large (Comparative Example 2), thepermanent set becomes large. When the molecular weight of compound (b)is high (Comparative Example 5), the shaped article becomes difficult tomake, In contrast, when the molecular weight of compound (b) is low(Comparative Example 4), the elongation is lowered and theantithrombotic property becomes poor.

When compound (d) is not used (Comparative Example 6) or the amountthereof is small, the permanent set is increased.

When compound (c) having two functional groups and compound (d) havingthree functional groups are incorporated in combination in the materialcomposition, the shaped article made of a polymeric material prepared byan additional polymerization thereof exhibits enhanced tear strength andtensile strength and a reduced permanent set. When this shaped articleis used as a balloon of a catheter, undesirable occurrence of thrombuscan be avoided or minimized.

Especially when compound (d) having a narrow molecular weightdistribution is used, the shaped polymeric article made from thematerial composition exhibits enhanced tensile strength and elongationand reduced permanent set, and, when this shaped article is used as aballoon of a catheter, undesirable occurrence of thrombus can be avoidedor minimized.

Example 22, Comparative Example 7

By the same procedures as described in Example 1, a material compositionwas prepared wherein the kind of compounds and the amount thereof werevaried as shown in Table 6 with all other conditions remaining the same.

The material composition was stirred at 70° C. by a mixer provided witha gear pump, and extruded under a pressure of 15 atm and at a rate of 2ml/sec into a cylindrical column having an inner diameter of 20 mm,maintained at a temperature of 120° to 150° C., to give a 5 lumen tubehaving a diameter of 2.3 mm.

The tube was allowed to stand in a thermostatic chamber at 110° C. for24 hours whereby the material composition was additionally polymerizedto give a tube for catheter. The evaluation results of the tube areshown in Table 6.

                  TABLE 6                                                         ______________________________________                                                           Example  Com. Ex.                                                             22       7                                                 ______________________________________                                        Prepolymer                                                                    Polyfunctiona1                                                                isocyanat (a)  m-mol!                                                         Diphenylmethane diisocyanate                                                                     100      100                                               Compound (b)  m-mol!                                                          Polyoxytetramethylens glycol                                                                     50       50                                                Number average molecular                                                                         1000     1000                                              weight (Mn)                                                                   Mw/Mn ratio *1     1.86     2.2                                               Chain extender                                                                Compound (b)  m-mol!                                                          Polyoxytetramethylene glycol                                                                     15       15                                                Number average molecular                                                                         1000     1000                                              weight (Mn)                                                                   Mw/Mn ratio *1     1.86     2.2                                               Compound (c)  m-mol!                                                          1,4-Butanediol     32       34                                                Compound (d)  m-mol!                                                          Trimethylolpropane 2        --                                                Antikinking test  mm!                                                                            30       17                                                Distortion recovery  %!                                                                          90       70                                                Collective evaluation                                                                            A        C                                                 as tube material                                                              ______________________________________                                         *1 Mw/Mn ratio: Ratio of weight average molecular weight/number average       molecular weight                                                         

As seen from Table 6, when a material composition comprising compound(b) and compound (c) but not comprising compound (d) is used(Comparative Example 7), the antikinking property and distortionresistance are not satisfactory. In contrast, the material compositionof the present invention (Example 20) results in an additionallypolymerized material giving a shaped article exhibiting a goodantikinking property and distortion resistance.

Example 23

A reactor was flashed with nitrogen gas and was charged with 100milli-moles of diphenylmenthane diisocyanate and charged 45 milli-molesof an etyhylene oxide-propylene oxide (ratio of 6/4 by mole) copolymerhaving a number average molecular weight of 1,000 and a weight averagemolecular weight/number average molecular weight ratio of 1.95. Thecontent was maintained at 90° C. for 1 hour to conduct an additionalpolymerization. Then, 25 milli-moles of an ethylene oxide-propyleneoxide (ratio of 6/4 by mole) copolymer having a number average molecularweight of 1,000 and a weight average molecular weight/number averagemolecular weight ratio of 1.86, 17 milli-moles of 1,4-butanediol, 3milli-moles of trimethylolpropane and dioxane were incorporated into thereactor, and the mixture was maintained at 80° C. for 3 hours to conducta reaction. Then ethanol was added to stop the reaction whereby asolution of a material composition was prepared.

The thus-prepared solution was coated on the inner wall of the pump ofan auxilliary pump made of plasticized polyvinyl chloride. A sheet madeof an antithrombotic polyurethane-silicone material was adhered onto thethus-formed coating to make an auxiliary artificial heart. Theevaluation results thereof are shown in Table 7.

Comparative Example 8

By the same procedures as described in Example 23, a materialcomposition was prepared and an auxiliary artificial heart was madetherefrom wherein the compounds used and the amounts thereof were variedas shown in Table 7 with all other conditions remaining the same.

                  TABLE 7                                                         ______________________________________                                                           Example  Com. Ex.                                                             23       8                                                 ______________________________________                                        Prepolymer                                                                    Polyfunctional                                                                isocyanate (a)  m-mol!                                                        Diphenylmethane diisocyanate                                                                     100      100                                               Compound (b)  m-mol!                                                          Ethylene oxide-propylene                                                                         45       45                                                oxide copolymer                                                               Number average molecular                                                                         1000     1000                                              weight (Mn)                                                                   Mw/Mn ratio *1     1.66     2.2                                               Chain extender                                                                Compound (b)  m-mol!                                                          Ethylene oxide-propylene                                                                         25       25                                                oxide copolymer                                                               Number average molecular                                                                         1000     1000                                              weight (Mn)                                                                   Mw/Mn ratio *1     1.86     2.2                                               Compound (c)  m-mol!                                                          1,4-Butanediol     17       17                                                Compound (d)  m-mol!                                                          Trimethylolpropane 3        --                                                Adhesion Retention  %!                                                                           88       74                                                ______________________________________                                         *1 Mw/Mn ratio: Ratio of weight average molecular weight/number average       molecular weight                                                         

As seen from Table 7, the shaped polymeric article (polymer coating)made from the material composition of the present invention exhibits agood retention of adhesion.

Industrial Applicability

A shaped article composed of a polymeric material prepared by anadditional polymerization of the material composition of the presentinvention exhibits a high tear strength, a high tensile strength, alarge elongation, a reduced permanent set, a reduced toxicity and a goodantithrombotic property.

Therefore, the above-mentioned shaped article is useful as catheterssuch as a tube catheter and a balloon catheter, an artificial heart, anartificial vessel and an artificial valve. The shaped article exhibits ahigh antithrombotic property even when it is used as parts for which ahigh stretchability is required, and therefore, it is especially usefulas a balloon member of a medical balloon catheter.

We claim:
 1. A shaped article of a tubular balloon form comprising apolymeric material prepared by an additional polymerization of:(a) apolyfunctional isocyanate, (b) a compound having a molecular weight of600 to 3,500 and two functional groups capable of being additionallypolymerized with an isocyanate group, (c) a compound having a molecularweight not larger than 500 and two functional groups capable of beingadditionally polymerized with an isocyanate group; and (d) a compoundhaving a molecular weight not larger than 700 and at least threefunctional groups capable of being additionally polymerized with anisocyanate group; wherein the sum of the functional groups capable ofbeing additionally polymerized with an isocyanate group, in compounds(c) and (d), is 1 to 35 moles per 100 moles of the isocyanate groups inpolyfunctional isocyanate (a), the amount of the functional groupcapable of being additionally polymerized with an isocyanate group, incompound (d), is 0.1 to 18 moles per 100 moles of the isocyanate groupsin polyfunctional isocyanate (a), the amount of the functional groupcapable of being additionally polymerized with an isocyanate group, incompound (b), is 60 to 100 moles per 100 moles of the isocyanate groupsin polyfunctional isocyanate (a), and the sum of the functional groupscapable of being additionally polymerized with an isocyanate group, incompounds (b), (c), and (d), is 80 to 110 moles per 100 moles of theisocyanate groups in polyfunctional isocyanate (a).
 2. The shapedarticle according to claim 1, wherein the weight average molecularweight/number average molecular weight ratio of compound (b) is lessthan
 2. 3. The shaped article according to claim 1, whereinthe sum ofthe functional groups capable of being additionally polymerized with anisocyanate group, in compound (c) plus compound (d), is 3 to 35 molesper 100 moles of the isocyanate groups in polyfunctional isocyanate (a),the amount of the functional group capable of being additionallypolymerized with an isocyanate group, in compound (d), is 1 to 10 molesper 100 moles of the isocyanate groups in polyfunctional isocyanate (a),the amount of the functional group capable of being additionallypolymerized with an isocyanate group, in compound (b), is 70 to 95 molesper 100 moles of the isocyanate groups in polyfunctional isocyanate (a),and the sum of the functional groups capable of being additionallypolymerized with an isocyanate group, in compounds (b), (c), and (d), is85 to 105 moles per 100 moles of the isocyanate groups in polyfunctionalisocyanate (a).
 4. The shaped article according to claim 1, wherein thefunctional groups capable of being additionally polymerized with anisocyanate group, in compounds (b), (c), and (d), are hydroxyl groups oramino groups.
 5. The shaped article according to claim 1, whereinpolyfunctional isocyanate (a) is an aromatic diisocyanate, compound (b)is a polyether-diol, compound (c) is a diamine or a diol, and compound(d) is a triamine or a triol.
 6. The shaped article according to claim1, wherein polyfunctional isocyanate (a) is diphenylmethanediisocyanate, compound (b) is polyoxytetramethylene glycol, compound (c)is ethylene diamine or 1, 4-butanediol, and compound (d) istrimethylolpropane.
 7. The shaped article according to claim 1, whereinthe ratio of compound (c) to compound (d) is such that:the amount of thefunctional group capable of being additionally polymerized with anisocyanate group, in compound (c), is 70 to 97% by mole based on the sumof the functional groups capable of being additionally polymerized withan isocyanate group, in compound (c) plus compound (d), and the amountof the functional group capable of being additionally polymerized withan isocyanate group, in compound (d), is 3 to 30% by mole based on thesum of the functional groups capable of being additionally polymerizedwith an isocyanate group, in compound (c) plus compound (d).
 8. Theshaped article according to claim 1, wherein the shaped article has atensile strength of 15 to 50 MPa, an elongation of at least 550% and apermanent set of not larger than 20%.
 9. The shaped article according toclaim 1, which has a tensile strength of 18 to 40 MPa, an elongation ofat least 600%, and a permanent set of not larger than 15%.
 10. A processfor making a shaped article of a tubular balloon form comprising apolymeric material prepared by an additional polymerization of:(a) apolyfunctional isocyanate, (b) a compound having a molecular weight of600 to 3,500 and two functional groups capable of being additionallypolymerized with an isocyanate group, and (c) a compound having amolecular weight not larger than 500 and two functional groups capableof being additionally polymerized with an isocyanate group, and (d) acompound having a molecular weight not larger than 700 and at leastthree functional groups capable of being additionally polymerized withan isocyanate group; wherein the sum of the functional groups capable ofbeing additionally polymerized with an isocyanate group, in compounds(c) and (d), is 1 to 35 moles per 100 moles of the isocyanate groups inpolyfunctional isocyanate (a), the amount of the functional groupcapable of being additionally polymerized with an isocyanate group, incompound (d), is 0.1 to 18 moles per 100 moles of the isocyanate groupsin polyfunctional isocyanate (a), the amount of the functional groupcapable of being additionally polymerized with an isocyanate group, incompound (b), is 60 to 100 moles per 100 moles of the isocyanate groupin polyfunctional isocyanate (a), and the sum of the functional groupscapable of being additionally polymerized with an isocyanate group, incompounds (b), (c), and (d), is 80 to 110 moles per 100 moles of theisocyanate groups in polyfunctional isocyanate (a); said processcomprising mixing polyfunctional isocyanate (a) and part of compound (b)together to form a mixture; heating the mixture; adding the remainder ofcompound (b), compound (c), and compound (d) to the heated mixture,while being stirred; shaping the resulting mixture into a tubular form,and then, heating the tubular form at a temperature of 60° to 170° C.11. The process for making a shaped article of a tubular balloon formaccording to claim 10, wherein said shaping of the mixture into atubular form is carried out by a reaction extrusion shaping method. 12.A balloon catheter comprising a catheter tube having a shaped article ofa tubular balloon fitted to a tip portion of said catheter tube;saidshaped article of a tubular balloon form being made of a polymericmaterial prepared by an additional polymerization of: (a) apolyfunctional isocyanate, (b) a compound having a molecular weight of600 to 3,500 and two functional groups capable of being additionallypolymerized with an isocyanate group, and (c) a compound having amolecular weight not larger than 500 and two functional groups capableof being additionally polymerized with an isocyanate group, and (d) acompound having a molecular weight not larger than 700 and at leastthree functional groups capable of being additionally polymerized withan isocyanate group; wherein the sum of the functional groups capable ofbeing additionally polymerized with an isocyanate group, in compounds(c) and (d), is 1 to 35 moles per 100 moles of the isocyanate groups inpolyfunctional isocyanate (a), the amount of the functional groupcapable of being additionally polymerized with an isocyanate group, incompound (d), is 0.1 to 18 moles per 100 moles of the isocyanate groupsin polyfunctional isocyanate (a), the amount of the functional groupcapable of being additionally polymerized with an isocyanate group, incompound (b), is 60 to 100 moles per 100 moles of the isocyanate groupsin polyfunctional isocyanate (a), and the sum of the functional groupscapable of being additionally polymerized with an isocyanate group, incompounds (b), (c), and (d), is 80 to 110 moles per 100 moles of theisocyanate groups in polyfunctional isocyanate (a).
 13. The ballooncatheter according to claim 12, wherein the weight average molecularweight/number average molecular weight ratio of compound (b) is lessthan
 2. 14. The balloon catheter according to claim 12, wherein the sumof the functional groups capable of being additionally polymerized withan isocyanate group, in compound (c) plus compound (d), is 3 to 35 molesper 100 moles of the isocyanate groups in polyfunctional isocyanate(a),the amount of the functional group capable of being additionallypolymerized with an isocyanate group, in compound (d), is 1 to 10 molesper 100 moles of the isocyanate groups in polyfunctional isocyanate (a),the amount of the functional group capable of being additionallypolymerized with an isocyanate group, in compound (b), is 70 to 95 molesper 100 moles of the isocyanate groups in polyfunctional isocyanate (a),and the sum of the functional groups capable of being additionallypolymerized with an isocyanate group, in compounds (b), (c), and (d), is85 to 105 moles per 100 moles of the isocyanate groups in polyfunctionalisocyanate (a).
 15. The balloon catheter according to claim 12, whereinthe functional groups capable of being additionally polymerized with anisocyanate group, in compounds (b), (c), and (d), are hydroxyl groups oramino groups.
 16. The balloon catheter according to claim 12, whereinpolyfunctional isocyanate (a) is an aromatic diisocyanate, compound (b)is a polyether-diol, compound (c) is a diamine or a diol, and compound(d) is a triamine or a triol.
 17. The balloon catheter according toclaim 12, wherein polyfunctional isocyanate (a) is diphenylmethanediisocyanate, compound (b) is polyoxytetramethylene glycol, compound (c)is ethylene diamine or 1, 4-butanediol, and compound (d) istrimethylolpropane.
 18. The balloon catheter according to claim 12,wherein the ratio of compound (c) to compound (d) is such that:theamount of the functional group capable of being additionally polymerizedwith an isocyanate group, in compound (c), is 70 to 97% by moles basedon the sum of the functional groups capable of being additionallypolymerized with an isocyanate group, in compound (c) plus compound (d),and the amount of the functional group capable of being additionallypolymerized with an isocyanate group, in compound (d) is 3 to 30% bymole based on the sum of the functional groups capable of beingadditionally polymerized with an isocyanate group, in compound (c) pluscompound (d).
 19. The balloon catheter according to claim 12, whereinthe shaped article has a tensile strength of 15 to 50 MPa, an elongationof at least 550% and a permanent set of not larger than 20%.
 20. Theballoon catheter according to claim 12, wherein the shaped article has atensile strength of 18 to 40 MPa, an elongation of at least 600% and apermanent set of not larger than 15%.